[Ffmpeg-devel] [Ffmpeg-devel-old] Re: avi out is buggy

Thomas Herrmann ollo.diab
Mon May 9 13:24:44 CEST 2005

Michael Niedermayer <michaelni <at> gmx.at> writes:

> Hi
> On Monday 09 May 2005 12:08, Thomas Herrmann wrote:
> > Hi,
> >
> > it seems the avi output of ffmpeg is buggy in the way that AC3 sound gets
> > out of sync over time. The sound just drifts apart from the video. This is
> > true too with AAC coded sound, while MP2 seems to be fine.
> >
> > To reproduce this I take a MPEG sample containing a MPEG2 video stream and
> > an AC3 audio stream and do:
> >
> > ffmpeg -i sample_w_ac3.mpg -vcodec copy -acodec copy out.avi
> >
> > While playing this file with mplayer, the sound starts in time with the
> > video, but drifts away quickly.
> stream copy from mpeg to avi isnt synchronizable, mpeg has timestamps, avi 
> does not, so frame drop / audio resampling might be needed but its not 
> possible with stream copy
> -> bug closed / invalid

Ok, but your answer does not help me to generate usable video file.

I was asking what output format and/or ffmpeg options should I use to transcode
a MPEG file containing a MPEG2 video stream and an AC3 audio stream to a video
file (avi, mpg, mov, ... ???) containing a h264 video stream and a ac3/aac
audion stream?

I tried:

ffmpeg -i sample_w_ac3.mpg -vcodec h264 -acodec copy -sameq -hq out.avi

which leads to asynchronous output, so does:

ffmpeg -i sample_w_ac3.mpg -vcodec h264 -acodec aac -sameq -hq out.avi

Thanks,    Thomas

> [...]

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